The Internet is a decentralized network of computers that can communicate with one another via the Internet protocol (IP). Although the Internet has its origins in a network created by the Advanced Research Project Agency (ARPA) in the 1960's, it has only recently become a worldwide communication medium. To a large extent, the explosive growth in use and traffic over the Internet is due to the development in the early 1990's of the worldwide Web (WWW), which is one of several service facilities provided on the Internet. Other facilities include a variety of communication services such as electronic mail, telnet, Usenet newsgroups, internet relay chat (IRC), a variety of information search services such as WAIS and Archie, and a variety of information retrieval services such as FTP (file transfer protocol) and Gopher.
The WWW is a client-server based facility that includes a number of servers (computers connected to the Internet) on which Web pages or files reside, as well as clients (Web browsers), which interface the users with the Web pages. Specifically, Web browsers and software applications send a request over the WWW to a server requesting a Web page identified by a Uniform Resource Locator (URL) which notes both the server where the Web page resides and the file or files on that server which make up the Web page. The server then sends a copy of the requested file(s) to the Web browser, which in turn displays the Web page to the user.
The topology of the WWW can be described as a network of networks, with providers of network service called Network Service Providers, or NSPs. Servers that provide application-layer services as previously described may be described as Application Service Providers (ASPs). Sometimes a single service provider does both functions within a single business
In recent years, broadband access technologies, such as digital subscriber line (DSL), cable modems, asynchronous transfer mode (ATM), and frame relay have facilitated the communication of voice, video, and data over the Internet and other public and private networks. Because broadband technologies are typically deployed by a single transport service provider, like a Regional Bell Operating Company (RBOC), their Regional and Access Networks (RAN) are often shared by many NSPs and ASPs offering services that range from Internet access and VPN access to Voice over IP, Video on Demand, and Gaming. Up until recently, a given Customer Premises Network (CPN) would have been connected to a single service provider in a generic way, however a new standard for RAN service (DSL Forum TR-059) provides a RAN architecture that allows simultaneous access to multiple NSPs and ASPs and for differentiating the data transport service provided by a RAN to these service providers.
Moreover, broadband access technology has allowed service providers to expand their content and service offerings to both business and home users. For example, a user may subscribe to multiple services or applications, such as voice service, Internet access service, a video service, a gaming service, etc. from one or more service providers. These services and/or applications may be delivered over a single network connection, such as a DSL line. Unfortunately, with multiple new connectivity options and applications that require specific characteristics from the network, there is also a need to establish QoS and bandwidth allocation among multiple services and/or applications so as to customize the content delivery according to the users' and/or providers' preferences.
The foregoing approach, however, assumes that applications are elastic and can adapt to the available network capacity. Not all applications are elastic, however, and for traditional telecommunications services, connection admission control has been used to control the aggregate load on the network and to help assure customer satisfaction. Admission Control (AC) is thus an aspect of a network service definition for certain services.